So it looks like you're building with the -W4 (warning level 4) and -WX (treat warnings as errors) flags turned on, and stb_image has a few internal warnings, which then get treated as errors by your compiler. They're simple warnings to fix, so they should probably be cleaned up by Sean at some point. In the mean time, you have a couple of options.

You could drop your warning level down to 3, or stop compiling with warnings as errors (This probably isn't what you want to do)